Redox reactions, short for oxidation-reduction reactions, are chemical reactions that involve the transfer of electrons between two species/Electrochemistry/Redox_Chemistry/Oxidation-Reduction_Reactions). During a redox reaction, some species undergo oxidation, or the loss of electrons, while others undergo reduction, or the gain of electrons. The species that is oxidized is the reducing agent, and the species that is reduced is the oxidizing agent/Electrochemistry/Redox_Chemistry/Oxidation-Reduction_Reactions).

Redox reactions are all around us, from the burning of fuels to the corrosion of metals, and even the processes of photosynthesis and cellular respiration involve oxidation and reduction. In order to understand redox reactions, it is important to understand oxidation and reduction reactions individually. Oxidation may be defined as the loss of electrons from a substance, while reduction may be defined as the gain of electrons by a substance.

Redox reactions are different from ordinary redox reactions in organic chemistry, where many reactions carry the name but do not actually involve electron transfer. Instead, the relevant criterion for organic oxidation is gain of oxygen and/or loss of hydrogen.

We can identify redox reactions by looking for changes in oxidation numbers over the course of a reaction. If an atom is oxidized, its oxidation number increases, and it is the reducing agent. If an atom is reduced, its oxidation number decreases, and it is the oxidizing agent/Electrochemistry/Redox_Chemistry/Oxidation-Reduction_Reactions).

Overall, redox reactions are important chemical reactions that involve the transfer of electrons between two species. They are all around us and play a crucial role in many natural and industrial processes.